Fluorescent lamp lighting circuit



July 28, 1959 w. A. CHARBONNEAUX ,8

' FLUORESCENT LAMP LIGHTING CIRCUIT 2 sheets-Sheet 1 Filed May 25. 1953 LINE LAMP

LAMP

FIG. 5.

INVENTOR. WILSON A. CHARBONNEAUX FIG. 6.

July-28,1959 w. A. CHARBONNEAUX 2,897,403

FLUORESCENT LAMP LIGHTING CIRCUIT File d May 25. 1953 '2 Sheets-Sheet Z 7 5/4 I i 6' L I! I f- WT LAMP LINE v 4 24 FIG. 7.

INVEN TOR.

WILSON A. CHARBONNEAUX FLUORESCENT LAMP LIGHTING CIRCUIT Wilson A. Charhonneaux, Dayton, Ohio Application May 25, 1953, Serial No. 356,965

4 Claims. (61. 315103) This invention relates to certain new and useful improvements in fluorescent lamp lighting circuits.

At the present time, there is a widespread and growing use of fluorescent and similar gas-filled discharge-type lamps for interior illumination in homes, plants, factories, and warehouses. This type of lamp is conventionally used with a ballast which provides the necessary high starting voltage and, furthermore, limits operating current. Conventional ballasts usually comprise a combined autotransformer and choke, but such devices have several disadvantages, such as a continuous high power loss, a lagging power factor which adds to the normal lagging power factor of other loads, and temperature rise during operation which creates insulation problems and limits practical use to conventional 110 v. and 240 v. lighting circuits.

It is, therefore, the primary Object of the present invention to provide fluorescent lighting circuits by which fluorescent lamps, and, particularly, the single pin hot cathode type lamps, can be started at relatively low temperatures across high voltage circuits and operated with a minimum of current consumption without undue power loss and, if desired, with a leading power factor.

It is another object of the present invention to provide fluorescent lighting circuits which are substantially more economical than existing fluorescent lighting circuits, both as to initial insulation costs, as well as operating costs.

It is a further object of the present invention to pro vide fluorescent lighting circuits by which a multiplicity of fluorescent lamps can be lighted and economically operated on higher voltage circuits, that is to say, for instance, a 440 v. circuit and similar circuits of the type usually available in industrial plants.

With the above and other objects in view, my invention resides in the novel features of form, construction, arrangement, and combination of parts presently described and pointed out in the claims.

In the accompanying drawings (two sheets):

Figures 1 to 10, inclusive, are schematic wiring diagrams showing various fluorescent lighting circuits embodying the present invention.

Broadly speaking, the present invention resides in the discovery that fluorescent lamps and, more particularly, single pin hot cathode type lamps of the so-called slimline type can be very efliciently started at ordinary room temperature and even at lower ambient temperatures by the utilization of an A.C. series circuit consisting of a choke coil, a capacitor in series with the lamp, and an inexpensive relay in a shunt circuit around the lamp. The relay functions to charge up the capacitor very quickly to a potential equal to l.4l R.M.S. line voltage. This capacitor potential is, in effect, vectorially additive to the peak-line potential, that is to say, the voltage at the top of a half cycle curve. The relay is so arranged that it will become fully energized and open the shunt circuit of the lamp When the voltage across the capacitor is maximum. Since the lamp acts as a very high resistance element before lighting, the capacitor will remain charged to its maximum potential until the lamp lights. If the lamp does not light the instant that the contacts open, the voltage of the charged capacitor will add to the peak voltage of the following cycle. This combined potential is sufliciently in excess of the ionization voltage of the lamp to cause the lamp to flash and become lighted. Since the maintenance or operat-- ing potential of such a lamp is much lower than its ionization potential, the lamp will be maintained in lighted condition on ordinary line voltage. In this connection, it should be noted that all references herein to a line imply an A.C. line.

Referring now in more detail and by reference characters to the drawings, which illustrate practical embodiments of the present invention, Figure 1 schematically represents a fluorescent lamp lighting circuit comprising a choke R a capacitor C a series switch S and a fluorescent lamp of the single pin hot cathode or socalled slim-line type, all being connected in series. The series relay S comprises a coil 1, a spring leaf contactor blade or armature 2, and a contactor point 3. The blade or armature 2 and contactor point 3 are normally in contactive engagement to form a shunt circuit around the lamp L and provides a means for quickly charging the capacitor C to a voltage of 1.41 times the root mean square volatge of the line.

As soon as voltage is applied across the line, current will flow through the choke coil R capacitor C and the coil 1 of the series relay S and thence through the shunt connection 4 around the lamp L to complete the circuit charging the capacitor C If the voltage applied across the line, for example, is 480 v., the capacitor C will be charged up to a potential of approximately 677 v., which will be additive to a substantial component of the line voltage, so that a potential well in excess of 750 v. is momentarily imposed across the lamp L Assuming, for instance, that a GE. 96T l2 lamp is used having a rated minimum starting voltage of 625 volts, it will be evident that the series coil of the relay will cause the lamp shunt toopen at the instant sulhcient current builds up in the series circuit, and that the time of opening would coincide with the time of maximum potential on the capacitor, and furthermore that one cycle later another peak voltage equal in value and direction will be added to the capacitor voltage left remaining, thus imposing a voltage across the lamp equal to 2.82 times the root mean square value of applied line voltage, which, in the case of a 480 v. line, would equal 1354 v. Actually, the capacitor voltage available under the circumstances of the presumed example is greater than 677 v. because the resistance in the circuit is relatively low, and the circuit, although not resonant, is in a condition approaching resonance. -It should be noted in this connection that the blade or armature 2 of the series relay S is spring biased or otherwise resiliently urged into circuit-closed position when the coil 1 is de-energized, but its mechanical closing action is slow, relatively speaking, as compared with the charging rate of the capacitor C and the other electrical time constants of the circuit. Thereby, the coil 1 of the relay S will become re-energized so quickly that the blade or armature 2 will be prevented from returning to closed or contact-making engagement with the contactor point 3.

Figure 2 is a schematic wiring diagram of a modified fluorescent lamp lighting circuit substantially similar to the circuit shown in Figure 1 and comprising a choke coil R a series relay S a capacitor C and a lamp L all substantially similar to the choke coil R relay S capacitor C and lamp L above described. The capacitor C however, is included in the shunt circuit so as to leave the operating circuit inductive, that is to say, having a lagging R1 n e e with. h amp. he wi f s er if hi titst @e f de astin i e a n at ame amount of capacitance can be addedto raise the power f 1; as may be desired. v

liigure 3 is a schematic wiring diagram of a further ns d a m Q fls te asn m lighting. i c e a e Pr e aveati a as de i ns ta t a plurality of lamps in series where the lamps eaeh indi w vidually have a starting voltage below the line voltage. $99995? or e am it wa des ed; w? rl thfee tfiIllGE. slim-line tubes across a 4810 v li'neJ Such tubcs eacli'havfe a starting voltage of 430 v. and an. opera rigyoltage of 95y. Hence,to avoid excessive curren consuming reactance, such tubes may be best opgr t d, resents and can be so utilized by employing a starting circuitenibodyingthe present invention. Such comprises a choke'coil" R a capacitor C lamps L3, L L arranged in series with series relays S S S Eaeh of the relays S S S includes a series coil 5, a Sipi ipgbiasedgblad e or armature 6, and a contactor point 7'. iii addition, the relays S S include potential windiaefi e tati e With the three relays S S S closed, the potential of the line voltage of 480v v. is actually imposed directly on the first lamp, that is to say, the lamp L and this illlight immediately since the applied voltage is well n ,x ess ofits starting potential. Immediately, curreiit will flow and the lamp L will, in efiect, become a se ds-auset st? he time? dra '2 e i cin mas 4.05 v. o t a hs s et e? r th second lamp L Since this is lower than required starting voltage, lamp Liwould not light up, but as lamp L becomes, in street, a conductorfthe circuit'arouud lamp L is actually the same basic circuit ofFig ure 1 and the capacitor C3 charges up to supply the starting voltage just as above described in connection with Figure l. The, relay S contains a series coil Sand a potential coil {5, neither of which, taken alone, can pull the relayopen, but when current flows through lamp L the potential coil 3, becomes energized and adds its effect to that of the cries coil 5, which is also energized. Hence, lamp Lifbejcomes lighted and the relay S cuts out. Thereupon, lamp L becomes aconductive element in the circuit drawing 95 v. and the line voltage available to start the third lamp L is, in effect, reduced to the same basic eirc uit of Figure 1 again and lamp L will consequently be lighted. The relays 8 ,8 will not open onfeither the potential or series" coils alone,but will remain open if eit 'r coil is energized. Thepotential coils 8, 9, there for prevent the circuit from recycling and the series relay S operates to disconnect the potential coils 8, 9, when allthe lamps are lightedf" i lfiigure 4 is a schematic wiring diagram of a further modified form of fluorescent lamp lighting circuit of the t fpr a purpose, s' ar tolfigure 3, and designed tofpioyide for starting a pl i ty oflamps in successive order and operating them in series. This circuit comprises a choke coil R a capacitor C first second, third, fougth. lamps If, L", L L and a series relay S e are in 10 and. sw n in de co t 1 with an arcuatecontactor segment 12 which is spring biased so as to be initially engaged simultaneously with contact points 13, 14, 15. The relay S is also provided with a potential coil 16, which functions to prevent recycling in. the event of tube failure and is in series with a manual reset button 17; Both line voltage and series current, that is to say, lamp voltage, are needed to pull in the relay armature 11. When the coils of the relay S are energized, the armature swings over to break contact in successive order with such contact points at intervals greater than one cycle of the applied current. Assuming, as before, that four 48T12 G.E. slim-line lamps are used, across a 480 v. line, the initial line voltage will start the first lamp L and thereupon, through action of the relay S the basic circuit of Figure 1 will be set up in successive ordcr around each of the other four lamps L", I}, and L Once the magnetic circuit is closed, the line potential will hold the armature down to prevent recycling. la the event of single lamp failure, all the lamps of; the fixture go. out and stay out until replacement of thedefective lamp is made. In order to make it possible for the maintenance. man to. check each lamp re placement Without leaving the fixture or interrupting other lighting fixtures, the normally closed manual reset button may be opened to permit the fixture to recycle a at Q.-. lV s ha he n a naess men an cer to the: circuit shown i n Figure 4 except that a series relay $1? s; antenna the ma a r e Switch 17- =i is? t is di etenq e s rwi of Figure 5 campuses shake 9911 R e ared? Ct u a L L12. L enew s n a. er e re w h a e e e tively identical, for all substantial purposes, with the unique y e ib s. lem a R Q LZU L9, n

In i "and, he e es relay 57" W l Open t matically when all the are lit, thus cutting out the P9 e i ,e l 67- F nite a schema i Wining diagram a u er notified. farm f; flsqreiss t amp i t n irc e aqe'ne t present n en i n; Thi i c i mp i es a haise ell 3? seres q G e es relay a has L sad as. m eda .8- In effect, i circuit is substantially to the circuit shown in Figure l. Ihe'impedance 1 8 howeven limits the current when the lamp is out, butd oes not prevent the lamp L from r in Figure 7 is a schematic wiring diagram of a further modified form of fluorescent lamp lighting circuit and comprises a choke coil R a capacitor C a series relay 3 having a series coil 19. and a potential coil 20. In series with these elements is a lamp L The poteutial coilZti operates to hold the relay in and thereby prevents, cycling.

Figure 8 is" a schematic wiring diagram of a further modified form of fluorescent lamp lighting circuit em bodying the present invention comprising a ballastB internally consisting of a series connected choke coil and capacitor, in efiec't, comparable to the elements R C of the basic circuit of Figure 1. In addition, the circuit of Figure 8 includes a potential relay 5, a lamp L 5, the latter being associated with a contact 21 which opens when the lamp is removed. The relay 5 will pull down and, open the shunt circuit around the lamp when its coil is energized, In this circuit, the time constant must be such that the, capacitor in the ballast B will charge up during the first half cycle of the impressed alternating, current. The potential relay S opens the lamp shunt circuit at the peak of the first half cycle of impressed voltage simultaneously as the charge on the capacitor reaches the point of optimum value. By this means itis possibie, generally preferable, to use a potential relay instead of series relay. The contact $1 at Fiesta 5. n t e senti t6 h operation of t circuit, but is shown to illustrate how'the circuit, or anyof the previously described circuits having potential relays, may be reset for operation whenever the lamp is removed from the contact-breaking socket.

Figure 9 is a schematic wiring diagram of a further modified form of fluorescent lamp lighting circuit embodying the present invention and is substantially identical in all respects to the previously described circuit of Figure 8 comprising a ballast B of the same type as the ballast B a lamp L and difiering only from the circuit of Figure 8 in that a thermo-switch T is substituted for the potential relay S Figure 10 is a schematic wiring diagram of a further modified form of fluorescent lamp lighting circuit embodying the present invention comprising a ballast B of the same type as the ballast B a lamp L a capacitor O, a glow tube switch G and a thermo-switch T having a manual reset button 22. When potential is applied across the line, the glow tube switch G will close the shunt circuit to charge the capacitor in the ballast B and in due course the thermo-switch T will reach a temperature which causes the shunt circuit to open. The capacitor C is merely an are-suppression condenser to prevent radio interference. If the lamp L goes out, the thermo-switch T will remain open, thus, when the lamp is replaced, it is necessary to opcrate the manual reset button 22 to initiate lighting operation.

It should be understood that changes and modifications in the form, construction, arrangement, and combination of the several parts of the fluorescent lamp light circuit may be made and substituted for those herein shown and described without departing from the nature and principle of my invention.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

l. A lighting circuit comprising a single pin hot cathode type fluorescent lamp, a line connected to a source of current having an RMS potential greater than the normal operating potential of the lamp but less than the ionization potential of said lamp, one terminal of said lamp being connected to one side of the line, a choke coil, a capacitor, and a relay forming a series circuit, said series circuit being connected to the other terminal of the lamp and to the other side of the line, and a shunt circuit across the terminals of the lamp and adapted to be opened and closed by the relay, so that when said potential is applied across the line, current will flow through the capacitor, choke coil and shunt circuit to charge the capacitor, and when the voltage across the capacitor reaches a peak value in excess of the ionization potential of the lamp, the relay will open the shunt circuit and the capacitor will discharge through the lamp.

2. A lighting circuit comprising a single pin cathodetype fluorescent lamp, a line connected to a source of alternating current having an RMS potential greater than the normal operating potential of the lamp but less than the ionization potential of said lamp, said lamp being connected across the line, a relay having a pair of normally closed contacts and actuating means for opening said contacts when said actuating means is energized, and a choke coil, a capacitor and said normally closed contacts being in series and forming a charging circuit, said charging circuit being connected across the line and by-passing the cathode-electrodes of said lamp, said choke coil and actuating means also being in series with the cathode-electrodes of said lamp so that when said potential is applied to the line current will flow through the charging circuit and charge the capacitor to a peak voltage substantially in excess of the ionization potential of the lamp, and when the said capacitor is charged to said peak voltage, it will discharge through and ionize the lamp and at the same time the current through said actuating means will open said contacts and allow current to flow through the choke coil, the actuating means, and the lamp.

3. A lighting circuit comprising a single pin cathodetype fluorescent lamp, a line connected to a source of alternating current having an RMS potential greater than the normal operating potential of the lamp but less than the ionization potential of said lamp, said lamp being connected across the line, a relay having a pair of normally closed contacts and an actuating coil for opening said contacts, and a choke coil, a capacitor, said contacts, and said actuating coil being in series and forming a charging circuit, said charging circuit being connected across the line and by-passing the cathode-electrodes of said lamp, said choke coil, capacitor, and actuating coil also being in series with the cathode-electrodes of said lamp so that when said potential is applied to the line current will flow through said charging circuit and charge the capacitor to a peak voltage substantially in excess of the ionization potential of the lamp, and when the capacitor is charged to said peak voltage it will discharge through and ionize the lamp and at the same time the current through said actuating coil will open the contacts and allow current to flow through the choke coil, the capacitor, the actuating coil, and the lamp.

4. A lighting circuit comprising a single pin hot cathode-type fluorescent lamp, a line connected to a source of alternating current having an RMS potential greater than the normal operating potential of the lamp but less than the ionization potential of said lamp, said lamp being connected across the line, a relay having a pair of normally closed contacts and a coil for opening said contacts when said coil is energized, and a choke coil, a capacitor and said normally closed contacts being in series and forming a charging circuit, said charging cir cuit being connected across the line and by-passing the cathode-electrodes of said lamp, said choke coil and relay coil also being in series with the cathode-electrodes of said lamp so that when said potential is applied to the line current will flow through the charging circuit and charge the capacitor to a peak voltage substantially in excess of the ionization potential of the lamp, and when the said capacitor is charged to said peak voltage, it will discharge through and ionize the lamp and at the same time the current through said relay coil will open said contacts and allow current to flow through the choke coil, the relay coil and the lamp.

References Cited in the file of this patent UNITED STATES PATENTS 2,030,426 Blok Feb. 11, 1937 2,170,457 Lord Aug. 22, 1939 2,423,031 Kurtz June 24, 1947 2,487,714 Ludvigsen Nov. 8, 1949 FOREIGN PATENTS 593,415 Great Britain Oct. 16, 1947 

